Chronic ingestion of enthanol impairs the control of gonadotropin secretion in male and female rats. The proposed studies would investigate physiologic mechanisms that might mediate the inhibitory action of ethanol by testing two hypotheses: (1) ethanol treatment slows the frequency of pulsatile LH release; (2) the LH control system in chronically alcoholic rats has a heightened sensitivity to the negative feedback actions of gonadal steroids. Confirmation of either or both these hypotheses would account for previous observations on serum LH levels during ethanol administration. Moreover, a slowing in frequency of pulsatile LH release following alcohol treatment would suggest a hypothalamic site of action and would provide the foundation for future studies on neurochemical mechanisms of action of ethanol. These studies will be performed in male and female rats chronically treated as weanlings or adults with an ethanol-containing liquid diet. Adult groups will consist of gonad-intact, castrated, and castrated, steroid-implanted animals. Each experimental rat will be matched to three controls: isocaloric pair-fed, weight-restricted, and ad lib-fed animals. The acute effects of ethanol will also be studied in other groups of untreated, castrated rats. LH concentrations will be measured by RIA in frequent blood samples obtained serially through right atrail catheters, and LH pulses will be analyzed using a computer program (PULSAR). Frequency and amplitude of pulsatile LH secretion, as well as the dose-response curves for steroid suppression of this hormone, will be compared in alcoholic and control rats. Furthermore, the known ability of estradiol to induce an afternoon surge of LH in ovariectomized rats will be tested in female alcoholic animals.